Bunions are deformities of bones and the joint found on a person's foot, causing pain for any individual having them. A bunion is often associated with hallux abducto valgus, the movement of the great toe laterally. Bunions are progressive and may become painful and debilitating. They are typically caused by poor biomechanics of the foot and footwear which may aggravate the condition.
A bunionectomy is a surgical procedure to remove painful bunions, by reforming the metatarsal. Typically, bunionectomy surgery involves correction of the foot by reconstructing bones and joints. There are numerous ways to correct bunions, the most common of which is the chevron osteotomy. In a chevron osteotomy, the bone is cut at the distal end. The cut is made in a V-shape near the distal metacarpal joint, which allows the entire toe to be moved laterally to the correct alignment. A small metal screw is fixed to the joint to provide stability. The chevron ostetomy is inherently more stable than a single cut osteotomy as two surfaces are in contact, and thus eliminating the likelihood that the bones may slip post operatively.
More specifically, a chevron osteotomy is used for correction of mild to moderate hallux vallgus deformities, allowing for a small reduction of the angle between the first and second metatarsal bones. Thus, the procedure is ideal for bunions that are not particularly pronounced. A V-shaped cut into the distal aspect of the first metatarsal near a metatarsal head allows the distal aspect to be translated (for example, 45 mm) in a lateral direction.
Recurrence of the bunion may occur if the metatarsal experiences a change in alignment after surgery. Thus, secure fixation of any cut metatarsal bone sections is important to ensure a successful bunionectomy fusion procedure. Wolff's law states that bones respond to loading conditions. (Angle Orthod. 2004 February; 74(1):3-15. A 2003 Update of Bone Physiology and Wolff's Law for Clinicians. Frost H M. Source Department of Orthopaedics, Southern Colorado Clinic, 3676 Parker Blvd., Pueblo, Colo. 81008-9000, USA.). An ideal fusion is one having solid and sustained bone contact at the conclusion of a surgical procedure and also keeping sustained bone contact for the weeks following the surgical procedure for the bone remodeling process to unite the bones. Failure to maintain proper fixation to keep sustained bone contact can result in misalignment, malunion, nonunion, and ongoing pain for the patient. Plating requires screws placed in small distal bone segments, which is impractical, as this may split the bone. Staples are low profile, but have limited compression ability, and usually cannot compress more than a millimeter. Additionally, compression is typically only at the tip and not uniform, which may potentially alter the fusion surface contact.